In the fifth and last boss, crunch and Cortex are fighting you. He first
jumps on the red pad, rocks fall down. Then, whenever he hits the ice
pad, you can beat them without even moving. Just run to the back of the
battle arena where the lightning blasters are crammed more close that
the other ones. This allows the ice boulders to go wherever without
touching you, and you don't have to move at all, until crunch launches
his next elemental attack.